We propose that neurosteroids, endogenous positive modulators of GABAAR function, and their synthetic analogues, may hold promise as treatments for anxiety disorders. The present study is designed to fill gaps in understanding between cellular-level inquiry and in vivo effects. An important premise of this work is that network studies in simple systems can give us insight into the relevant effects of clinically promising drugs, including aspects of drug actions not easily derived from a receptor-level or cellular-level understanding. A secondary premise of this exploratory proposal is that because natural WT networks in dissociated culture are self-organizing into network topologies reminiscent of in vivo networks, key aspects of network dysfunction in disease may also be reconstituted. Recent work supports the radical idea that dysfunction associated with stress and anxiety can be recapitulated in dissociated culture networks. Our work extends research into this potentially important area. Aim 1 will test the hypothesis that cellular accumulation reduces the effect of exogenous neurosteroids on network function and accounts for steroid-specific rebound of neuronal activity. These studies use multi-electrode array recordings and are unique in probing the gray area between pharmacokinetics and pharmacodynamics as an important contributor to drug effects on networks. Aim 2 will explore the nature of network dynamics in models deficient in the GABAA receptor gamma2 subunit. The ability of neurosteroids to correct network dynamics will be assessed. These studies will lend insight into changes in network dynamics induced by receptor changes believed to underlie anxiety disorder. The studies will also provide new information on the effect of therapeutic drugs not easily discernible from previous levels of analysis.